﻿function Base64() {

    var self = this;

    var keyStr = "ABCDEFGHIJKLMNOP" +
             "QRSTUVWXYZabcdef" +
             "ghijklmnopqrstuv" +
             "wxyz0123456789+/" +
             "=";

    var base64Test = /[^A-Za-z0-9\+\/\=]/g;

    function validate(input) {
        if (base64Test.exec(input)) {
            return false;
        }
        return true;
    }
    
    function encode(array) {
        var output = "";
        var chr1, chr2, chr3 = "";
        var enc1, enc2, enc3, enc4 = "";
        var i = 0;

        do {
            chr1 = array[i++];
            chr2 = array[i++];
            chr3 = array[i++];

            enc1 = chr1 >> 2;
            enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
            enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
            enc4 = chr3 & 63;

            if (isNaN(chr2)) {
                enc3 = enc4 = 64;
            } else if (isNaN(chr3)) {
                enc4 = 64;
            }

            output = output +
               keyStr.charAt(enc1) +
               keyStr.charAt(enc2) +
               keyStr.charAt(enc3) +
               keyStr.charAt(enc4);
        } while (i < array.length);

        return output;
    }

    function decode(input) {
        var output = [];
        var chr1, chr2, chr3 = "";
        var enc1, enc2, enc3, enc4 = "";
        var i = 0;

        input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");

        do {
            enc1 = keyStr.indexOf(input.charAt(i++));
            enc2 = keyStr.indexOf(input.charAt(i++));
            enc3 = keyStr.indexOf(input.charAt(i++));
            enc4 = keyStr.indexOf(input.charAt(i++));

            chr1 = (enc1 << 2) | (enc2 >> 4);
            chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
            chr3 = ((enc3 & 3) << 6) | enc4;

            output.push(chr1);

            if (enc3 != 64) {
                output.push(chr2);
            }
            if (enc4 != 64) {
                output.push(chr3);
            }

        } while (i < input.length);

        return output;
    }

    self.encode = encode;

    self.decode = decode;

    self.validate = validate;

}